In a typical wireless communications network, wireless devices, also known as mobile stations, terminals, and/or User Equipments, UEs, communicate via a Radio Access Network, RAN, with one or more core networks. The RAN covers a geographical area which is divided into cells, with each cell being served by a base station, e.g. a radio base station, RBS, or network node, which in some networks may also be called, for example, a “NodeB”, “eNodeB”, “eNB” or Access Point, AP. A cell is a geographical area where radio coverage is provided by the radio base station at a base station site or an antenna site in case the antenna and the radio base station are not collocated. One radio base station may, however, serve one or more cells. The base stations communicate over the air interface which may also be called radio interface operating on radio frequencies with the wireless devices within range of the base stations.
A Universal Mobile Telecommunications System, UMTS, is a third generation mobile communication system, which evolved from the second generation, 2G, Global System for Mobile Communications, GSM. The UMTS terrestrial radio access network, UTRAN, is essentially a RAN using wideband code division multiple access, WCDMA, and/or High Speed Packet Access, HSPA, for user equipments. In a forum known as the Third Generation Partnership Project, 3GPP, telecommunications suppliers propose and agree upon standards for third generation networks and UTRAN specifically, and investigate enhanced data rate and radio capacity. In some versions of the RAN as e.g. in UMTS, several base stations may be connected, e.g., by landlines or microwave, to a controller node, such as a radio network controller, RNC, or a base station controller, BSC, which supervises and coordinates various activities of the plural base stations connected thereto. The RNCs are typically connected to one or more core networks.
Specifications for the Evolved Packet System, EPS, have been completed within the 3rd Generation Partnership Project, 3GPP, and this work continues in the coming 3GPP releases. The EPS comprises the Evolved Universal Terrestrial Radio Access Network, E-UTRAN, also known as the Long Term Evolution, LTE, radio access, and the Evolved Packet Core, EPC, also known as System Architecture Evolution, SAE, core network. E-UTRAN/LTE is a variant of a 3GPP radio access technology wherein the radio base station nodes are directly connected to the EPC core network rather than to RNCs. In general, in E-UTRAN/LTE the functions of a RNC are distributed between the radio base stations nodes, e.g. eNodeBs in LTE, and the core network. As such, the Radio Access Network, RAN, of an EPS has an essentially flat architecture comprising radio base station nodes without reporting to RNCs.
Network Controlled Device-to-Device, D2D, Communication
Network controlled Device-to-Device, D2D, communication facilitates direct communication between wireless devices utilizing the cellular spectrum of the wireless communication network. Due to mobility, varying traffic loads and changes in the radio environment, the wireless communication network may dynamically switch the communication mode between two communicating wireless devices. For this purpose, by means of existing techniques, the wireless communication network may use control signaling to switch the communication mode for two wireless devices in a cell between regular cellular communication, i.e. a cellular mode in which the two wireless devices are communicating via a network node, and direct communication, i.e. a D2D mode in which the two wireless devices are communicating directly with each other. At such communication mode selecting instances, often simply referred to as Mode Selection, MS, the wireless communication network may also configure the characteristics of the cellular or D2D bearer and allocate/reallocate cellular resources used for the cellular or D2D bearers. The purpose of having the MS controlled by the wireless communication network is to ensure high radio resource utilization, manage QoS and at the same time protect the cellular layer from interference caused by D2D communication between wireless devices.
Full Duplex, FD, Communication
Conventionally, wireless communication networks are designed on the premise of Half Duplex, HD, communication that does not allow simultaneous transmission and reception of radio signals on the same frequency channel. Examples on HD transmission and reception schemes comprise, for example, HD Frequency-Division Duplexing, HD FDD, and HD Time-Division Duplexing, HD TDD. These schemes enable separating the transmitted and received signals at a radio transceiver either in frequency or in time or in both. In contrast, Full Duplex, FD, communication enables simultaneous transmission and reception of radio signals. For FD TDD, this may even take place on the same carrier frequency. However, for FD FDD, the transmission and reception of radio signals take place on different carrier frequencies.
It has been generally assumed that FD communication is not practically viable in a wireless network communication because of the large amount of Self-Interference, SI, that is caused by a radio transmitter at the radio receiver. For example, assuming a transmitted signal of 100 mW transmit power and a noise floor at around −90 dBm, the transmit SI must be cancelled by ˜90 dB to reduce the SI at the radio receiver to similar level as the set noise floor. This should be considered in view of that commercial isolators normally only may provide ˜20 dB of transmit/receive isolation. At present, accomplishing SI cancellation at this order of magnitude is typically not economically viable, if feasible at all.
However, recent developments suggest that this assumption may be questioned in the near future, which raises questions of how to take full advantage of wireless device capable of FD communication in a wireless communication network; and also, how the wireless communication network is to control D2D communication between such FD capable wireless devices.
US 2013/0254277 A1 disclose a wireless communication network which allows an initiation of a D2D communication, using HD or FD communication, based on the range between the D2D pair of wireless devices. However, it does not disclose how a wireless communication network should control the D2D communication in order to take full advantage of the D2D pair of wireless device capable of FD communication in the wireless communication network, such as, for example, how to perform mode selection, MS.